Storefront PayPal shopping cart and checkout

I recently realized that my cupcake selling business needed a store front so I could itemize each cupcake for sale, and to make checkout easier for my customers. Not having a storefront confused the customer too much from buying the cupcakes to the "Submit" button. Now that I have the storefront, when someone clicks on an item to purchase, everything works right except the checkout button to buy through the paypal system checkout doesn't work. How do I link the storefront shopping cart and the customers order to give the customer ease of using their card to purchase from paypal and giving them a receipt for their exact purchase and then informing me a sale was made and then I can make the customers order? Or do I have to solve this on the paypal website help?